A variable valve mechanism 90 of a conventional example illustrated in FIGS. 7A and 7B includes a switch arm 91 driven by a cam, a main arm 92 that drives a valve of an internal combustion engine when swinging, and a switch pin 93 that is mounted on the main arm 92 so as to be displaceable. The switch pin 93 is displaced to a disconnected position C− so that the variable valve mechanism 90 is switched to a disconnected state as illustrated in FIG. 7A, and the switch pin 93 is displaced to a connected position C+ so that the variable valve mechanism 90 is switched to a connected state as illustrated in FIG. 7B.
As illustrated in FIG. 8A, during switching from the disconnected state to the connected state, if timing of the switching is inappropriate, the switch pin 93 protrudes to the connected position C+ while the switch arm 91 is swinging in an idle swing direction D1, so that the switch arm 91 comes below the switch pin 93. As a measure to prevent the switch arm 91 from being locked in such a case, a pressing surface 91a having a curved surface is formed at an end of the switch arm 91. With this configuration, as illustrated in FIGS. 9A to 9F, when the switch arm 91 swings in a return direction D2, the switch arm 91 presses a pin end surface 93a with the pressing surface 91a to the disconnected position C− so as to push back the switch pin 93.